NASA instruments document contraction of the boundary between the Earth's ionosphere, space

December 15, 2008

GREENBELT, Md. - Observations made by NASA instruments onboard an Air Force satellite have shown that the boundary between the Earth's upper atmosphere and space has moved to extraordinarily low altitudes. These observations were made by the Coupled Ion Neutral Dynamics Investigation (CINDI) instrument suite, which was launched aboard the U.S. Air Force's Communication/Navigation Outage Forecast System (C/NOFS) satellite on April 16, 2008.

The CINDI suite, which was built under the direction Principal Investigator Rod Heelis of the University of Texas at Dallas, includes both ion and neutral sensors and makes measurements of the variations in neutral and ion densities and drifts.

CINDI and C/NOFS were designed to study disturbances in Earth's ionosphere that can result in a disruption of navigation and communication signals. The ionosphere is a gaseous envelope of electrically charged particles that surrounds our planet and it is important because Radar, radio waves, and global positioning system signals can be disrupted by ionospheric disturbances.

CINDI's first discovery was, however, that the ionosphere was not where it had been expected to be. During the first months of CINDI operations the transition between the ionosphere and space was found to be at about 260 miles (420 km) altitude during the nighttime, barely rising above 500 miles (800 km) during the day. These altitudes were extraordinarily low compared with the more typical values of 400 miles (640 km) during the nighttime and 600 miles (960 km) during the day.

The height of the ionosphere/space transition is controlled in part by the amount of extreme ultraviolet energy emitted by the Sun and a somewhat contracted ionosphere could have been expected because C/NOFS was launched during a minimum in the 11-year cycle of solar activity. However, the size of the actual contraction caught investigators by surprise. In fact, when they looked back over records of solar activity, they found that C/NOFS had been launched during the quietest solar minimum since the space age began.

This extraordinary circumstance is providing an unparalleled opportunity to study the connection between the interior dynamics of the Sun and the response of the Earth's space environment.
CINDI is a NASA sponsored Mission of Opportunity conducted by the University of Texas at Dallas. NASA's Explorer Program at Goddard Space Flight Center, Greenbelt, Md., managed the CINDI mission. The Explorer Program provides frequent flight opportunities for world-class scientific investigations from space within heliophysics and astrophysics.

The CINDI investigation is carried out as an enhancement to the science objectives of the C/NOFS satellite undertaken by the Air Force Research Laboratory and the Space and Missile Command Test and Evaluation Directorate.

For related images to this story, please visit:

For NASA's CINDI Web site, visit:

For the University of Texas at Dallas, CINDI web site, visit:

Air Force Research Laboratory Web site

NASA/Goddard Space Flight Center

Related Solar Activity Articles from Brightsurf:

Inhibiting epileptic activity in the brain
A new study shows that a protein -- called DUSP4 -- was increased in healthy brain tissue directly adjacent to epileptic tissue.

Merging solar cell and liquid battery produces long-lasting solar storage
Combining liquid chemical battery technology with perovskite solar cells has led to a new record in solar energy conversion within a single device.

Merging solar cell and liquid battery produces efficient, long-lasting solar storage
Chemists at the University of Wisconsin-Madison and their collaborators have created a highly efficient and long-lasting solar flow battery, a way to generate, store and redeliver renewable electricity from the sun in one device.

Solar wind samples suggest new physics of massive solar ejections
A new study led by the University of Hawai'i (UH) at Mānoa has helped refine understanding of the amount of hydrogen, helium and other elements present in violent outbursts from the Sun, and other types of solar 'wind,' a stream of ionized atoms ejected from the Sun.

Parker Solar Probe traces solar wind to its source on sun's surface: coronal holes
New data from the Parker Solar Probe, which got closer to the sun than any other spacecraft, allowed physicists to map the source of a major component of the solar wind that continually peppers Earth.

3D maps of gene activity
A three-dimensional computer model enables scientists to quickly determine which genes are active in which cells, and their precise location within an organ.

Is physical activity always good for the heart?
Physical activity is thought to be our greatest ally in the fight against cardiovascular disease.

Predicting terror activity before it happens
Data scientist have developed a model that utilizes publicly available data to accurately predict how lethal a terror organization will become in the future based on only its first 10 attacks.

Solar energy becomes biofuel without solar cells
Soon we will be able to replace fossil fuels with a carbon-neutral product created from solar energy, carbon dioxide and water.

Understanding brain activity when you name what you see
Using complex statistical methods and fast measurement techniques, researchers found how the brain network comes up with the right word and enables us to say it.

Read More: Solar Activity News and Solar Activity Current Events is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to